Choose the correct colour of the product for the following reaction.

The reaction is an azo coupling reaction.

The diazonium salt of sulfanilic acid acts as the electrophile, while 1-naphthylamine acts as the activated aromatic nucleophile.

Coupling occurs predominantly at the para position with respect to the $$-NH_2$$ group of 1-naphthylamine, forming an azo compound containing the linkage $$-N=N-$$.

The product possesses an extended conjugated system involving the benzene ring, the azo bridge, and the naphthalene ring.

This extensive $$\pi$$-conjugation lowers the energy gap between molecular orbitals, causing absorption in the visible region and giving rise to a strongly coloured azo dye.

The azo dye formed from diazotized sulfanilic acid and 1-naphthylamine is the dye produced in the Griess reaction and is characteristically red in colour.

Hence, the colour of the product is

$$\boxed{\text{Red}}$$

Therefore, the correct answer is

$$\boxed{\text{Option C}}$$